Magnetizing inrush current suppression device

Abstract

A magnetizing inrush current suppression device (6) that controls a breaker (2), wherein inter-pole capacitors (22U, 22V, 22W) are connected, and which opens / closes a connection between a transformer (3) and a three-phase alternating-current power supply (1) so as to control magnetizing inrush current. On the basis of the three-phase alternating current voltages (Vtu, Vtv, Vtw) on the transformer side of the breaker (2), the phase for which the absolute value is the largest or the phase for which the absolute value is the smallest, of the direct current components (Zdu, Zdv, Zdw) of the three-phase residual flux, is detected as the phase of interest. In addition, the breaker (2) is closed at the phase of interest when the phase of interest of the three-phase alternating current voltages (Vu, Vv, Vw) on the power supply side is a closing target phase (thetac1) having a wave-height value which is the reverse polarity of the polarity of the direct current component (Zdu, Zdv, Zdw) of the residual flux, and the breaker (2) is closed at the two phases other than the phase of interest when the phase of interest of the three-phase alternating current voltages (Vu, Vv, Vw) on the power supply side is a closing target phase (thetac2) which reaches zero after the closing target phase (thetac1).

Description

technical field [0001] The present invention relates to a magnetizing inrush suppressing device for suppressing a magnetizing inrush generated when a transformer is turned on to a power supply. Background technique [0002] Generally, it is known that a large excitation inrush current flows when the power is turned on and no-load excitation is performed with residual magnetic flux in the transformer core. The magnitude of this magnetizing inrush current becomes several times the rated load current of the transformer. If a large inrush current flows in this way, the system voltage fluctuates. When this voltage fluctuation is large, it may affect the requester. [0003] As a method of suppressing this magnetizing inrush current, it is known that when connecting a directly grounded three-phase transformer with three single-phase circuit breakers, one of the arbitrary phases is first connected, and then the remaining two phases are connected. Methods of suppressing magnetizin...

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Problems solved by technology

[0007] In the case of the residual magnetic flux having the AC component superimposed on the DC component in this way, it is difficult to obtain the intersection point of the residual magnetic flux and the permanent magnetic flux as described above.

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